1. Field
This disclosure generally relates to analytical instruments, and particularly analytical instruments for use with specimen holders that hold specimens or samples to be analyzed.
2. Description of the Related Art
There are numerous types of analytical instruments used for a variety of purposes, for example research, testing, and diagnostics. For example, some analytical instruments are used to detect biological substances, for instance proteins or DNA.
Many analytical instruments expose a specimen or sample of a material to be analyzed to electromagnetic energy and senses or otherwise detects a response of the specimen or sample to the exposure. For example, a specimen or sample may be exposed to illumination in one or more wavelengths or ranges of wavelengths of the electromagnetic spectrum. For instance, a specimen or sample may be exposed to or illuminated with electromagnetic energy in an optical portion of the electromagnetic spectrum, extending from infrared to ultraviolet and encompassing visible light as well as invisible light such as near infrared or near ultraviolet wavelengths. Many materials will reflect some wavelengths while absorbing other wavelengths. Some materials may reemit electromagnetic energy at a different or shifted wavelength in a phenomenon commonly referred to as fluorescence. This spectral response may be used to characterize the material.
Analytical instruments are often used with disposable specimen or sample holders which hold specimens or samples of the material to be analyzed. Specimen or sample holders may take the form of simple cuvettes or may be relatively more complicated microfluidic platforms with channels, wells, reservoirs, pumps, valves, etc. Such may come in a variety of shapes, typically plates with either a rectangular or circular profile. The specimen or sample holders are removably located in the analytical instrument.
In some instances, the specimen or sample holders also hold one or more reagents that are targeted to react with certain substances. Some reagents may for example fluoresce, aiding in identification of substances with which the reagents react.
The ability to accurately measure responses from specimens or samples is important. Achieving consistent illumination or excitation is important to producing accurate results. Such may be difficult due to alignment errors, particularly where the specimen or sample holder is removable. Typically high density of specimens or samples on a sample holder is desirable. However, closeness of specimens or samples may complicate analysis. Interference between sampling of neighboring areas or locations may also contribute to error or inaccuracies.
New approaches which may lead to improved accuracy in analytical instruments are desirable.